wget http://vault.centos.org/8.1.1911/AppStream/Source/SPackages/potrace-1.15-2.el8.src.rpm
rpmbuild --rebuild potrace-1.15-2.el8.src.rpm
...
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking for x86_64-redhat-linux-gnu-clang... no
checking for x86_64-redhat-linux-gnu-gcc... no
checking for x86_64-redhat-linux-gnu-cc... no
checking for x86_64-redhat-linux-gnu-c99... no
checking for x86_64-redhat-linux-gnu-mgcc... no
checking for x86_64-redhat-linux-gnu-c89... no
checking for x86_64-redhat-linux-gnu-pcc... no
checking for x86_64-redhat-linux-gnu-opencc... no
checking for x86_64-redhat-linux-gnu-sunc99... no
checking for x86_64-redhat-linux-gnu-suncc... no
checking for clang... clang
checking whether the C compiler works... no

Both gcc and clang are installed, and they do both work. Ugh. Will unpack the RPM and delve into this deeper after lunch.

Well, that only took an entire afternoon. For future reference, below are the steps I had to take
to build the Inkscape release from source. "modules" is the normal user for software development,
and "root" is, well, root.